Answer:
1) Last years' margin = Net operating income÷ Sales
= 240,000÷1,200,000
= 0.2= 20%
2) Last years' turnover = Sales ÷ Average operating assets
= 1,200,000 ÷ 600,000
= 2
3) Last years' return on investment = Margin ratio × turnover ratio
= 20% × 2 = 40%
4) Margin for this years' investment = Net operating income ÷ Sales
= 36,000 ÷ 240,000
= 0.15 = 15%